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Although the structural characterization of the major leukocyte cell surface mucin CD43 has proceeded rapidly, understanding its physiological function has been hindered by contradictory results. Here, Julie Ostberg and colleagues propose that the Roman god of two faces, Janus, provides a model that reconciles the roles attributed to CD43.

Considerable progress has recently been made in understanding the structure and ligand interactions of the T-cell antigen CD2, to the extent that CD2 is now a useful paradigm for considering the structural basis of cell-cell recognition. Here, Simon Davis and Anton van der Merwe review the new data and consider their implications for T-cell function in the context of CD2-knockout experiments.

Naturally occurring (autoimmune) antibodies reactive with phospholipids are found in normal rabbit and human sera. In this short article, Nico van Rooijen postulates that bacterial endotoxins trigger the production of these autoimmune antiphospholipid antibodies by CD5+ (Ly-1+) B cells. According to this postulate, the endotoxins, or their lipid-A-containing fractions, become inserted in cell membranes and induce the production of autoimmune IgM antibodies against surface antigens, such as phospholipids, of such cells.